The present invention relates to a storage management method and system, and more specifically to a method for monitoring the status of storage usage in a computer system having a large number of storage units. Compound computer systems in which a number of host computers carry out jobs while sharing, or exclusively using, logical areas allocated in storage units such as disks are in common use. In such compound computer environments, as the system becomes more large-scale or the jobs become more diversified, it is increasingly demanded that a large variety of data be handled efficiently by a storage subsystem. In addition, such demand needs to be satisfied while reducing the overall storage management cost. To meet these requirements, it is important to build an environment which allows the information on storage usage and file allocation to be obtained efficiently.
A number of methods for managing storage usage have been proposed. For example, Laid-open Patent Specification No. 2003-303054 discloses an arrangement in which each storage subsystem monitors and manages the storage usage inside it by itself. More specifically, each of the storage subsystems is provided with a management module, which constantly monitors the usage of each volume in it by the user's computers and informs the user of the storage usage status whenever there is a change in it. This arrangement allows storage usage to be monitored and managed efficiently, without getting the user's computer to be involved.